Not Applicable
Not Applicable
A stent is a radially expandable endoprosthesis which is adapted to be implanted in a body lumen. Stents are typically used in the treatment of atherosclerotic stenosis in blood vessels and the like to reinforce body vessels and to prevent restenosis following angioplasty in the vascular system. They have also been implanted in urinary tracts, bile ducts and other bodily lumen. They may be self-expanding or expanded by an internal radial force, such as when mounted on a balloon.
Delivery and implantation of a stent is accomplished by disposing the stent about a distal portion of the catheter, percutaneously inserting the distal portion of the catheter in a bodily vessel, advancing the catheter in the bodily lumen to a desired location, expanding the stent and removing the catheter from the lumen. In the case of a balloon expandable stent, the stent is mounted about a balloon disposed on the catheter and expanded by inflating the balloon. The balloon may then be deflated and the catheter withdrawn. In the case of a self-expanding stent, the stent may be held in place on the catheter via a retractable sheath. When the stent is in a desired bodily location, the sheath may be withdrawn allowing the stent to self-expand.
In the past, stents have been generally tubular but have been composed of many configurations and have been made of many materials, including metals and plastic. Ordinary metals such as stainless steel have been used as have shape memory metals such as Nitinol and the like. Stents have also been made of bio-absorbable plastic materials. Stents have been formed from wire, tube stock, etc. Stents have also been made from sheets of material which are rolled.
A number of techniques have been suggested for the fabrication of stents from sheets and tubes. One such technique involves laser cutting a pattern into a sheet of material and rolling the sheet into a tube or directly laser cutting the desired pattern into a tube. Other techniques involve cutting a desired pattern into a sheet or a tube via chemical etching or electrical discharge machining.
Laser cutting of stents has been described in a number of publications including U.S. Pat. No. 5,780,807 to Saunders, U.S. Pat. No. 5,922,005 to Richter and U.S. Pat. No. 5,906,759 to Richter. Other references wherein laser cutting of stents is described include: U.S. Pat. Nos. 5,514,154, 5,759,192, 6,131,266 and 6,197,048.
A typical laser cutting system relies on a laser to produce a beam which is conditioned as necessary via an optical unit and focused into a spot beam which is impinged against a hollow tube that is to become the stent. The hollow tube may be moved via a rotational motor drive and linear motion drive.
An example of a conventional laser for cutting a stent is a highly focused pulsed Nd:YAG laser which has a pulse duration in the range of approximately 0.1 to about 2.0 milliseconds. This is a long pulse time for cutting and characteristically produces a relatively large melt zone and heat affected zone (HAZ) on the metal. The conventional laser cutting process may result in the formation of melt dross and/or other debris forming on the cut tube.
In a more recent development, cutting and processing systems have been developed that incorporate a water column and laser such as is described in international publication number WO 01/75966 to SYNOVA Inc., of Lausanne, Switzerland. Such a system employs a laser-microjet that uses a laser beam contained within a waterjet as a parallel beam, similar in principle to an optical fiber achieved by a high index of refraction between fluid and air and/or inert atmosphere. While the use of water in a water/laserjet hybrid system may aid in preventing the formation and buildup of excess debris on the object being cut, an object, such as a tube being cut for use as an implantable medical device, cut in this manner will still require further cleaning and/or polishing processes prior to use.
In light of the above, a need exists to provide a medical device processing method and system wherein the processes of laser cutting, etching, cleaning and/or polishing of an object are combined into a reduced number of processes or steps, or in some embodiments a single process or step.
All U.S. patents and applications and all other published documents mentioned anywhere in this application are incorporated herein by reference in their entirety.
Without limiting the scope of the invention a brief summary of some of the claimed embodiments of the invention is set forth below. Additional details of the summarized embodiments of the invention and/or additional embodiments of the invention may be found in the Detailed Description of the Invention below.
A brief abstract of the technical disclosure in the specification is provided as well only for the purposes of complying with 37 C.F.R. 1.72. The abstract is not intended to be used for interpreting the scope of the claims.
The present invention is directed to a variety of embodiments. As indicated above, the use of a hybrid laser/water jet for the purpose of cutting is known. In embodiments of the present invention however, a novel type of laser/fluid jet mechanism is described wherein the use of water as a laser transmission media is supplanted or supplemented with a processing fluid such as one or more etchants, abrasives, polishes, cleaners, detergents, etc.
In the various embodiments of the invention, a processing fluid is suitable for transmission of laser energy therethrough without causing significant disruptive affect on the laser energy being transmitted. As a result the processing fluid through which the laser energy is directly transmitted must have a high transparency in order for the laser wavelength to be transparent.
In at least one embodiment the work piece is a hollow tube of a material suitable for constructing a stent. Such a tube may be at least partially constructed from, stainless steel, nickel, titanium, palladium, gold, tantalum, or any other metal or alloy, such as nitinol, thereof suitable for constructing a stent. In at least one embodiment the tube is at least partially constructed from a polymer substance.
In at least one embodiment the hollow tube is a tube of material suitable for constructing a tubular medical device, or component thereof. In such an embodiment the processed tube may be utilized as, or a portion of: a hypotube, a catheter, a balloon, a sock, a sleeve, an embolic protection filter, etc.
In at least one embodiment the laser energy is transmitted to the work piece in a column of fluid, wherein the column of fluid transmitting the laser energy is within one or more additional columns of fluid. The laser transmission column may comprise a fluid that is different than the fluid of the adjacent or additional columns. For example the transmission column of fluid may comprise water, while one or more other columns of fluid may comprise one or more processing fluids, such as etchants, abrasives, polishes, detergents, cleaners, etc. In another example the transmission column comprises a solution of one or more processing fluids whereas an adjacent column or columns may comprise water and/or other fluid.
In the various embodiments described herein the fluid selected to transmit laser energy to the work piece must have a high transparency for the wavelength of the laser energy to be transmitted therethrough. It is necessary that the fluid through which the laser energy is transmitted is suitable to prevent significant optical loss or degradation of the laser energy transmitted therethrough.
In some embodiments one or more of the columns of fluid apply ultrasonic energy to the work piece. In some embodiments, one or more fluid columns are transmitted to the work piece at a frequency of about 20 KHz to about 40 KHz or greater frequency. In some embodiments the frequency is about 1 MHz or greater. In some embodiments the frequency is fixed, random, varying, cyclic and/or any combination thereof. In at least one embodiment, wherein multiple columns are applied to the work piece, different columns are applied to the work piece at different frequencies.
In at least one embodiment the processing fluid is a solution of at least one etchant, abrasive, polish, cleaner, detergent, etc. in combination with water.
In at least one embodiment the processing fluid comprises glycerin.
In at least one embodiment the processing fluid comprises fluorinated alcohol.
In at least one embodiment at least one column of fluid is a processing fluid such as fluorinated base etchant in combination with sulfates and/or peroxides and/or water, such as for example HF+H2SO4+H2O2+H2O. In at least one embodiment, the solution of HF+H2SO4+H2O2+H2O is provided at a ratio of 30/30/1/39.
In at least one embodiment at least one column of fluid comprises a fluid selected from the group comprising: a solution sodium hydroxide and water; a solution of ammonium bifluorite and water; a solution of fluoboric, nitric and water; a solution of hydrochloric acid and acetic acid; a solution of one or more non fluorinated etchants, and hydrogen peroxide; a solution of hydrofluoric, nitric and water; citric acid and any combination thereof.
In at least one embodiment the laser energy directed to the work piece is transmitted from a laser. The laser may be any type of laser including but not limited to diode lasers, YAG lasers, UV lasers, IR lasers, CO2 lasers, etc.
In some embodiments the laser energy and at least one column of fluid define a beam size or diameter, at a point of intersection on the work piece, of about 5 to about 120 microns or greater. In at least one embodiment the beam size is about 35 to about 60 microns.
In some embodiments the column of fluid comprises an electrolytic solution.
In some embodiments the column of fluid may be directed through manipulation of the fluid""s magnetic field.
In some embodiments the direction of the column of fluid may be deflected by manipulation of electrostatic forces. In at least one embodiment the column of fluid is passed by one or more electrostatic deflectors which are constructed and arranged to bend the fluid column in a desired manner around the surface of the deflector.
In some embodiments fluid is passed through a heating and/or a cooling mechanism prior to forming the fluid into a column.
These and other embodiments which characterize the invention are pointed out with particularity in the claims annexed hereto and forming a part hereof. However, for a better understanding of the invention, its advantages and objectives obtained by its use, reference should be made to the drawings which form a further part hereof and the accompanying descriptive matter, in which there is illustrated and described embodiments of the invention.